NNA: Bridging the Atomistic Deformation Mechanisms to the Microscopic Adhesive-to-Cohesive Fracture at Ice-Metal Interfaces

在寒冷表面上的冰积累是许多工程应用中非常关注的话题，包括飞机、风力涡轮机和在极地海域附近航行的船舶。然而，由于缺乏对许多基本问题的答案，例如冰是如何从金属表面脱落的，以及是什么控制着破裂类型从粘着性（冰-金属界面断裂）转变为内聚性（冰本身断裂）破裂的，因此，以最小功率输入的除冰（从冷表面分离冰）策略尚未建立。该研究项目将通过确定冰-金属材料体系中黏着-黏合断裂的基本机制来推进界面力学科学；将冰-金属界面结构与其冰黏附强度联系起来；并支持寻找比现有方法耗能少得多的除冰策略。该项目还将通过合理设计抑制或增强冰附着的材料，促进国家的健康、繁荣和福利，对在北极和寒冷天气下运行的广泛的安全关键基础设施产生影响，包括电信设备、电力线、汽车车辆、海洋船舶和海上石油平台，以及日常环境中的食品和运输部门。有了这些进展，该项目将通过对民用基础设施设计和工程的影响，为北极日益增长的海上商业提供支持，从而支持美国国家科学基金会关于导航新北极（NNA）的大构想。作为项目的一部分，教育和外展活动将侧重于夏季招收本科生，通过大学项目向妇女和少数民族学生进行外展，并通过门户网站传播软件。本项目将结合多物理场、多尺度的模拟和实验，即水的粗粒度建模、金属材料的新型并发原子连续体建模，以及在独特的结冰研究隧道设施中的实验，以阐明冰-金属材料系统中粘附-内聚界面断裂的相关物理原理。计算机模型将集成，以实现从原子到微观尺度的固液相互作用的多尺度模拟，同时考虑在实验设施中制作的冰-金属材料样品的真实微观结构。该研究将确定位错介导的塑性在黏着-黏合界面断裂中的作用，并量化冰-金属粘附强度及其对金属表面拓扑结构、化学和冰微观结构的敏感性。这些模型将以相关尺度的实验测量进行校准和验证。该项目还将为参与的学生提供广泛的知识和技能，包括结冰物理、防/除冰技术、力学、超级计算、材料加工和表征以及结冰隧道测试。为了说明金属表面的微小变化如何显著改变其冰附着强度，我们将在当地的初中和高中设计、制作和分发几个冰-金属材料系统套件。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Ice accretion over cold surfaces is a topic of great concern for numerous engineering applications, including airplanes, wind turbines, and marine vessels sailing near polar seas. However, a strategy of de-icing (detaching ice from cold surfaces) with minimal power input is not well-established yet due to the lack of answers to many fundamental questions, such as how does the ice shed from a metallic surface and what controls the conversion of fracture type from adhesive (fracture at an ice-metal interface) to cohesive (fracture within ice itself) cracking? This research project will advance the science of interfacial mechanics by identifying the fundamental mechanisms for the adhesive-to-cohesive fracture in an ice-metal material system; correlate an ice-metal interface structure with its ice adhesion strength; and support the search of de-icing strategies that consume far less power than existing approaches. The project would also advance the national health, prosperity, and welfare by enabling a rational design of materials that either inhibit or enhance ice adhesion, with implications for a wide range of safety-critical infrastructures operating in arctic and cold weathers, including telecommunication equipment, power lines, automotive vehicles, marine vessels, and offshore oil platforms, along with the food and transport sectors in everyday environment. With these advancements, this project will support the NSF Big Idea on Navigating the New Arctic (NNA) through impact on the design and engineering of civil infrastructure for an increasing marine commerce in the Arctic. As part of project, education and outreach activities will focus on hiring undergraduate students for the summer, performing outreach to women and minority students through university-based programs, and dissemination of software from a web-portal.This project will combine multi-physics, multi-scale simulation and experimentation, i.e., coarse-grained modeling of water, novel concurrent atomistic-continuum modeling of metallic materials, and experiments in a unique Icing Research Tunnel facility, to elucidate the underlying physics pertinent to adhesive-to-cohesive interface fracture in ice-metal material systems. The computer models will be integrated to enable multiscale simulation of solid-liquid interaction from the atomistic to the microscale, while accounting for the realistic microstructure of ice-metal material specimens fabricated in the experimental facility. The research will determine the role of dislocation-mediated plasticity in an adhesive-to-cohesive interface fracture, and quantify the ice-metal adhesion strength and its sensitivity to metal surface topology, chemistry, and ice microstructure. The models will be calibrated and validated with experimental measurements at relevant scales. This project will also provide participating students a broad range of knowledge and skills in icing physics, anti-/de-icing technology, mechanics, supercomputing, material processing and characterization, and icing tunnel testing. Several kits of ice-metal material systems will be designed, fabricated and distributed in local middle and high schools for illustrating how slight changes of a metal surface can significantly change its ice adhesion strength.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.